Blast Furnace: Combustion Technology

Equipment
Combustion Technology
Energy Consumption
Process Description
R&D Trends

The pressures on blast furnace operations to improve efficiencies while simultaneously reducing emissions are tremendous, and they continue to mount. The focus of the efforts to achieve these ends has been the combustion processes within the hot-blast stoves and the blast furnace proper.

Combustion of carbon monoxide-rich blast furnace off-gases within the hot-blast stoves is used to produce the hot-blast air. In older blast-stoves, metallic burners are typically used. These burners are located externally to the combustion chamber, and are placed at the bottom of the stoves. In newer blast-stoves, ceramic burners are employed. These burners include a mixing chamber and are installed directly within the combustion chamber.

Combustion within the blast furnace proper is being significantly affected by increased adoption of supplemental fuel injection. Supplemental fuels such as natural gas, pulverized coal, and oil, are typically injected through a lance inserted into the blowpipe leading up to the tuyere. The use of supplemental fuel injection, particularly natural gas, can introduce significant amounts of hydrogen into the furnace, which in turn affects the thermal balance. Due to high velocities, combustion of the hot-blast air and injected fuels only occurs once they are well into the furnace.

Agarwal, J. C. et al, 1994, Natural Gas Injection into Blast Furnaces, Operating Practice Update, Charles River Associates, Inc; GRI Report No. GRI-94/0405.